Double-break contact



Sept. 18, 1945. D. ELLIS Em 2,384,988

DOUBLE BREAK CONTACT Filed July 31, 1942 MOVABE CONTACT ASSEMBL Y INVENTORS WITNESSES:

m r De/berffi/ dogY en L.

- ATTORNEY Patented Sept. 18, 1945 2,884,9 8- DOUBLE-BREAK CONTACT Delbert Ellis and Owen L. Taylor, Wilkinsburgsz Par, assignors to Westinghouse Electric Corporation, East Pittsburgh,-Pa., a. corporation of Pennsylvania Application July 31, 1942, Serial No. 453,060

4 Claims.

This invention relates to a double break contact structure and, more particularly, to an improved mounting, for the movable contacts of such structure.

Double break contacts commonly comprise a pair of stationary contacts which are engageable' with a .pair of movable contacts carried by a conducting orbridging member. The conducting or bridging member is in turn mounted on an actuator support which is movable back and forth between different positions for moving the movable contacts into and out of engagement with the stationary contacts. The bridging member is usually mounted on its actuator support by a centrally located .guiding pin and stop member and spring which'biases the bridging member away from its support into engagement with the stop member and permits relative movement of the bridging memberwith respect to its actuator support to enable self alignment of the movable contacts With the stationary contacts. Considerable difiiculty has been encountered with conventional types of contact structures due to the bouncing of the contacts taking place upon opening and closing movements. The bouncing of the contacts is due to vibratory oscillating movement of the bridging member carrying the movable contacts about a transverse horizontal axis and leads to shortened life and Welding of the contacts. A main factor causing oscillation of the movable contacts about the transverse horizontal axis is the central location of the guiding andstopping pill whereby movement of the mass of the bridging member carrying the movable contacts is stopped near its center of rotation. In addition to the inherent'tendency of a mass to vibrate or oscillate when stopped nearv its center of rotation, the bouncing action is further aggravated by uneven distribution of weight with respect to the center of the bridging member where a central guiding and stopping pin is em-. ployed.

One of the principal objects of this invention is to provide a mounting for the movable contacts of a double break contact structure which will effectively eliminate bouncing of the contacts upon opening and closing movement thereof..

A further object of this invention is to provide a double break contact assembly comprising a bridging member resiliently mounted on an actuator support in which movement of the bridging member with respect to the actuator support is limited by stopping parts located at the ends of the bridging member.

A further object of this invention is to provide a double break contact assembly in which movement of a resiliently mounted bridging member is guided by parts located at thelo'ngitudinal'ends of the bridging member and in which such guiding parts are operative to frictionally damp vibratory movement of the bridging member about a transverse horizontal axis.

Other objects and advantages of this inven= tion will become apparent during thecourse of the following description taken in connection with the accompanying drawing, in which:

Figure 1 is an exploded view showing inperspective parts of a double break contact assembly constructed in accordance with the principles of F this invention;

Fig. 2 is a side elevational'view-showingthc parts of Fig. 1 assembled and showing their relation with respect to a pair of stationarycontacts, the support for the stationary contacts being shown in section; and

Fig. 3 is a side elevational view of a modified form of a movable contact assembly.

'Referring to the drawing, the numeral 8 designates an elongated conducting or bridging member carrying a'pair of button shaped contacts '2 and '3 spaced longitudinally thereof. Thebridging member is provided with an opening 4 located centrally thereof and has depending end portions 5 and B-.- These end portions are Partly cut away and re-shaped so that each of them has two parallel legs and a part interconnecting these legs, and one of the legs of each end portion is integrally connected with theb'ody or mainportion of the bridging member; The end portions 5 and 8 represent guiding parts and provide lateral guiding surfaces 1 and 8 and a stop surface 9. The entire bridging member I is preferably formed from a rectangular blank of suitable conducting material, such as copper, by suitable stamping operations.

The numeral Iii designates a spring which is located centrally of the bridging member I by a pin H which is employed to secure a guiding member l2 to an actuator support. The actuator support I3 is formed of insulating material and is provided with a cylindrical opening I centrally thereof and a longitudinal slot 15 in= tersecting with the opening M. The opening M has a smaller diameter at the bottom thanat the top. Aguiding member I2 is inserted in the opening 84 and the slot [5 of the support l3 and has guiding lugs I6 and H projecting from both ends, respectively, of the guiding member. Each of the lugs I5 and H has an abutting surface l8' and lateral guiding surface I 9. The

The slot 23 is made less than the thickness of the member I2 so that the legs 24 of the pin II will be cammed into tight'engagement with the bottom surface of the opening I 4 to hold the parts I2 arid I3 together. Thereafter, the spring I is positioned over the pin II with its lower end resting on the surface 2| of the guiding member I2. The bridging member I is then placed With its opening aligned with the axis of the spring I!) and pin II and is then moved downwardly to compress the spring I0 until the upper end of the pin I I is positioned within the opening 4.

Thereafter, the member I is rotated to move the stopping surface 9 on the U-shaped end portions 5 and 6 underneath the stopping surfaces I8 on the guiding lugs I6 and I1. Upon release of the bridging. member I, the bias of the spring II] will be effective to move the bridging member I outwardly to a position as limited by interengagement of the stopping surfaces 9 and IS.

-:The pin II functions only as an assembly and securing means in connection with the parts thus far described butis not designed to guide movement of the bridging member I with respect to its actuator support I3.

The contacts 2 and 3 carried by the bridging member I are adapted to engage the stationary contacts 25 and 26 carried by conducting leads 21 positioned within an insulating housing 28. The actuator support I 3 is adapted to be operated by any suitable form of actuating mechanism for moving the contacts 2 and 3 into and out of engagement with the stationary contacts 25 and 26. Since such actuating mechanism for double break contacts is Well known in the art and forms no part per se of this invention, the actuating mechanism for the support I3 has notbeen illustrated. The function of the mechanism is to move. the support I3 upwardl for closing the circuit and downwardly for opening it.

In the showing of Fig. 6 the contacts 2 and 3 are shown at their points of initial engagement with the stationary contacts 25 and 26. Upon further upward movement of the actuator support I3 to its final circuit closing position, the upper surface of the support I3 will be moved into the position as indicated by the dotted line 29 to effect a further compression of the spring I6. This arrangement permits the contacts 2 and 3 to align and make contact with the stationary contacts 25 and 26 in a manner well known in the art.

Movement of the bridging member I with respect to the actuator support I3 is controlled by engagement of the guiding surfaces I and 8 with the lateral guiding surfaces I9 on the projecting lugs I3 and I1. Interengagement of the guiding surface I9 with the guide surfaces I and B is effective to confine movement of the bridging member I to movement in a vertical plane containing the longitudinal center line 30 which passes through the center of the contacts 2 and 3. Heretofore, in most cases where a central guiding post Was employed a small amount of wear on the guiding post would permit rotation of the bridging member center line about a vertical axis 3I to a position such as indicated by the dotted line 32 in which the position of the stationary and movable contacts would not align properly. It will be apparent that an equivalent amount of wear on the interengaged surfaces I, I8 and IQ of this invention would not permit an equivalent amount of movement of the center line 30 about the vertical axis 3I out of the position shown in Fig. 1.

Interengagement of the guiding surfaces I and B with the guiding surfaces I9 in addition provides a frictional damping action which is ap- 'plied at the ends of the bridging member I and is effective to damp out any tendency of the bridging member I to vibrate or oscillate about its transverse horizontal axis 33. Such vibration or oscillation of the bridging member I about the axis 33 has caused the bouncing of the stationary and movable contacts, which has been heretofore found objectionable.

In addition, the stopping force, by which movement of the bridging member I with respect to its actuator support I3 under the bias of the spring Ill is limited, is applied at the ends of the bridging member I.

The stopping force is applied to the bridging member I by the engagement of the surfaces I8 on the guiding member I2 with the stop surfaces 9 at the longitudinal ends of the member I. Interengagement of the surfaces 9 and I8 functions to limit movement of the member I by the spring III with respect to the actuator support I3. In this manner the stopping force is applied as far from the center of mass'of the member I as possible and oscillation or bouncing due to applying the stopping force at the center of mass is eliminated. I

The modification shown in Fig. 3 is essentially the same as that illustrated in Figs. 1 and 2 from the standpoint of construction and. operation. The difference lies in the substitution oi springs 34 positioned adjacent the ends of the bridging member I and underneath the contacts 2 and 3. The location of the spring 34 near the ends of the bridging member I further reduces the tendency of, the member I to rotate about its horizontal transverse axis 33.

The double break contact structure of this invention is particularly adaptable for use with line starter switches and circuit control switches of similar size. In such switches, the bridging member usually has a length of from about 1%," to about 2%, width of from about A to about and the contacts 3 have a diameter of from about /4" to about Due to the size of the bridging member, it is difficult to secure a perfect balance of weight with respect to the center or an equal application of the spring bias on both sides. Uneven distribution of weight and spring bias obviously increases the tendency toward misalignment and contact bounce. These factors together with the size and spacial limitations within which the improved structure must be confined, renders doubly important the improved construction of this invention described above.

Since certain changes may be made in the above described construction and different embodiments of the invention can be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. A contact assembly comprising an elongated bridging member formed of conducting material, said material being cut away at each end thereof to provide a U-shaped end portion having parallel legs and a part connecting said legs together, each of said U-shaped portions having one of its legs integral with the body of said bridging member and being deformed so as to depend vertically downwardly from the body of said bridging member, an actuator support for said bridging member having a guiding member provided at opposite sides with two guiding lugs, respectively, extending outwardly into the space between said parallel legs of each of said portions respectively, and a spring for biasing said bridging member away from said support to a position with the said connecting part of said U-shaped portions abutting against said respective guiding lugs, said parallel legs of said portions having facing surfaces engaging said respective lugs for guiding the movement of said bridging member with respect to said support so as to confine such movement to a vertical plane containing the longitudinal axis of said bridging member.

2. A double break contact structure, comprising a pair of mutually spaced stationary contacts,

a movable elongated bridgin member with two spaced contacts for engaging said stationary contacts, respectively, an insulating support engaging said bridging member for free aligning movement of said member about an axis transverse of said member, spring means for biasing said member away from said support toward said stationary contacts, two guiding parts integral with said bridging member and disposed at both longitudinal ends, respectively, of said member outwardly of said contacts of said member, guiding means disposed on said support and engaging said two guiding parts frictionally so as to guide and damp vibratory oscillating movement of said member about an axis transverse to the longitudinal axis or said member.

3. In a double break contact structure having a pair of mutually spaced stationary contacts and a movable contact assembly, said assembly comprising an elongated bridging member with two spaced contacts for engaging said stationary contacts, respectively, an actuator support for said member, resilient means positioned between said support and member for biasing said member away from said support, said member having two guiding parts depending from the respective longitudinal ends of said member and positioned outwardly of said appertaining contacts, and said support having guiding means projecting from said support and engaging said respective depending parts frictionally so as to freely permit to said member limited movement relative to said support substantially in the vertical plane of its longitudinal center line while frictionally damping vibratory oscillating movements of said member about an axis transverse to said plane.

4. In a double break contact structure having a pair of mutually spaced stationary contacts and a movable contact assembly, said assembly comprising an elongated bridging member with two spaced contacts for engaging said stationary contacts, respectively, an insulating support for said member, said support and said member engaging each other for free aligning movement of said member about an axis transverse of said member, spring means for biasing said member away from said support toward said stationary contacts, guiding parts disposed at both longitudinal ends of said member, respectively, and disposed outwardly of said appertaining contacts, and guiding means seated in said support and bridging said guiding parts, respectively, for limiting the spring biased movement of said member relative to said support. 

